The spectrum of pathology of nontuberculous mycobacterial infections in open-lung biopsy specimens.

The diagnosis of pulmonary nontuberculous mycobacterial (NTM) infection may be difficult to establish unless open-lung biopsy is performed. Mycobacteria were present in resected lung tissues from forty patients at the Mount Sinai Hospital during the period 1969-1980. M. avium-intracellulare was cultured in 24 patients, M. tuberculosis in six, M. gordonae in three, and M. fortuitum in two. In five instances, mycobacteria were seen in smears of lung tissues but failed to grow in culture. Three distinct clinicopathologic groups of patients with NTM were recognized. (1) Eighteen patients had solitary pulmonary nodules resected with the clinical diagnosis of lung cancer. Histologically, they exhibited granulomas with varying degrees of necrosis. Mediastinal lymph nodes had no granulomas, except in one case. (2) Seven patients presented with roentgenologic evidence of bilateral, diffuse interstitial infiltration. M. avium-intracellulare or M. gordonae were isolated from lung tissue which histologically showed interstitial fibrosis and organizing pneumonia. In only one instance a few non-caseating epitheloid cell granulomas were found. Three of these patients had underlying malignancies treated with chemotherapy and one other had arthritis. The other three had no underlying diseases. (3) Three patients had multiple discrete infiltrates on chest roentgenograms. M. avium-intracellulare was isolated from their lung tissues. One of these patients exhibited necrotizing granulomatous vasculitis indistinguishable from Wegener's granulomatosis. It is apparent that classical "tuberculosis-like" granulomatous reaction is the most common histologic pattern but should not be expected in all patients with NTM infections.